1. How does the food change in consistency and form?
- The food undergoes several changes before it is absorbed by the body. In the mouth, mechanical digestion through chewing and chemical digestion from enzymes in saliva turns the food into smaller pieces and eventually becomes a mass called bolus. It then moves to the stomach where gastric juices that contain hydrochloric acid and enzymes, turn the bolus into a semi-fluid mass called chyme, also breaking down proteins through pepsin in the process. In the small intestine, digestive enzymes from the pancreas along with bile continue to break down the chyme—carbohydrates, fats, proteins—into smaller, basic units, i.e., glucose, fatty acids, and amino acids. As it continues through the small intestine, villi in the area absorb the nutrients found in the chyme; it remains liquid at this stage. Finally, as it travels through the large intestine, excess water from the stool along with electrolytes are absorbed turning the liquid of digested food into a harder mass called stool.
2. How could the body absorb the nutrients from the foods we eat?
- It all starts in the mouth where the breaking down of food into smaller pieces and the introduction of enzymes such as amylase break down complex carbohydrates into simple sugars. This continues through the later parts of the digestive system where the following occur:
- The stomach produces pepsin that breaks down proteins into amino acids.
- The liver produces bile that breaks down fats into fatty acids.
- The pancreas produces lipase that works in conjunction with bile to break down fats, as well as protease and amylase that break down proteins and carbohydrates into amino acids and glucose, respectively.
- These aforementioned processes are all important for the villi in the small intestine to be able to absorb the nutrients from the food that we eat.